SERS, which is a vibrational spectroscopic technique, is a type of Raman scattering which is performed near to surfaces comprising nano-scaled structures formed of metals such as gold, silver, or copper, or surfaces of nanoparticles prepared from the said metals, and which provides detailed information about the chemical structure of the molecule under investigation. The enhancement effect is the result of the charge transfer between the molecule under investigation and the nanostructured metal surface, and mostly the surface plasmon formation resulting from the overlapping of the frequency of the laser directed onto the analyzed sample and the oscillation frequencies of the electrons which enable conductivity of metal nanoparticles. Therefore, it is necessary to create surfaces where surface plasmons can be utilized effectively for improved enhancement.
The pathological identification of human tissue samples especially in cancerous tissues is difficult. This difficulty becomes more pronounced with certain tumor types. The conventional pathological tumor identification is performed by eye examination or certain spectroscopic techniques. The pathologist examines the sample by eye and after staining with several staining methods and other techniques, tries to identify whether the tissue sample is tumorous or healthy or the degree of the tumor. The pathological identification of tissue samples with spectroscopic techniques can be faster and more reliable. The conventional pathological tissue differentiation methods are methods which require detailed investigation on the sample, and through which, it is sometimes difficult to obtain an accurate result despite the said detailed investigation. Therefore, in the recent years, using the spectroscopic techniques for differentiation that is based on the composition of the molecular structures composing the tissue has increased in importance. One of the most important spectroscopic techniques applied in the present day is vibrational spectroscopy. There is a number of studies and methods related to these techniques based on IR, NIR and Raman. All these approaches have their own specific difficulties and disadvantages. While water in the sample can be a problem in IR based techniques, Raman requires increased spectral collection times since scattering is very weak, and the data obtained by using both IR and Raman techniques should definitely be evaluated statistically.
The U.S. Pat. No. 5,261,410 known in the art discloses a method that can differentiate if a tissue sample is malignant, benign or a normal tissue. This invention claims that when the sample is irradiated with NIR light, different tissue samples generate distinguishable Raman spectra.
The U.S. Pat. No. 5,261,410 and international patent No. WO2008001978 known in the art describe the use of silica nanoparticles prepared with silver nanoparticles in a surface-enhanced Raman scattering based method. The method in the invention is claimed that it can be used in detection of specific diseases such as leukemia and breast cancer.